Heat-insulated railway tank cars and a method of making the same

ABSTRACT

There is disclosed a heat-insulated railway tank car and a method of making the same, comprising positioning one or more barriers on an elongated inner liner, the barrier having a flexible portion and a rigid portion, sliding an elongated outer shell onto the inner liner while radially compressing the flexible portion of the barrier, the barrier thus defining separate fluid-tight compartments between the inner liner and the shell, and filling the compartments with an insulating substance.

CARS AND A METHOD OF MAKING THE SAME United States Patent 1151 3,653,333

Taylor 51' Apr. 4, 1972 541 HEAT-INSULATED RAILWAY TANK 3,390,644 7/1968Kraus kopf ..105/35s 3,172,566 3/1965 M11111 et al.. 105/360 GravesAnderson 105/360 lnventor: William A. Taylor, Sharpsville, Pa.

Primary Examiner-Arthur L. La Point Asslgnee' 2:31 32:22: 1 TranspomnonCor Assistant ExaminerRichard A. Bertsch p g Attorney-Prangley, Clayton,Mullin, Dithmar and Vogel Filed: Jan. 21, 1970 pp 4,506 [57] ABSTRACTThere is disclosed a heat-insulated railway tank car and a method ofmaking the same, comprising positioning one or as}? fik tgg morebarriers on an elongated inner liner, the barrier having a Fieid 29/455flexible, portion and a rigid portion, sliding an elongated outer shellonto the inner liner while radially compressing the flexible portion ofthe barrier, the barrier thus defining separate References cuedfluid-tight compartments between the inner liner and the shell, UNITEDSTATES PATENTS and filling the compartments with an insulatingsubstance.

3,547,047 12/ 1970 Needham 105/360 5 Claims, 8 Drawing Figures 60 20 63I0 24 i I i2 3/ 30 50 ,4 40b l7 I2 PATENTED R 4 I972 SHEET 1 BF 3 R m ML m w m I y M I m f L H W HEAT-INSULATED RAILWAY TANK CARS AND A METHODOF MAKING THE SAME This invention relates generally to heat-insulatedrailway tank cars and to methods of making the same.

It is a general object of the invention to provide a railway tank carthat is especially adapted to transport a variety of hot and coldladings, and a method of making such a tank car.

Another object of the invention is to provide a method of making arailway tank car, comprising providing an elongated inner liner that hasa longitudinal axis, positioning on the inner liner a barrier having asubstantially rigid portion and a radially adjacent substantiallyflexible portion, providing an elongated outer shell having an insideradius less than the distance between the longitudinal axis and theoutside surface of the barrier, sliding the outer shell onto the innerliner while radially compressing the flexible portion, the barrierthereby defining separate fluid-tight compartments between the innerliner and the shell, and filling the compartments with an insulatingsubstance.

Another object of the invention is to provide a railway tank car,comprising an elongated inner liner having a longitudinal axis, abarrier on the inner liner and having a substantially rigid portion anda substantially flexible portion radially adjacent to the rigid portion,an elongated outer shell having an inside radius less than the distancebetween the longitudinal axis and the outside surface of the barrier,the elongated outer shell encompassing the inner liner and compressingsaid flexible portion, whereby the barrier defines separate fluid-tightcompartments between the inner liner and the outer shell, and aninsulating substance in the compartments.

Another object of the invention is to provide an improved method ofmaking a railway tank car of the character described that involves aminimum number of simple steps which may be carried out in an economicalmanner.

Still another object of the invention is to provide an improved methodof making the railway tank car, wherein the inner liner and the outershell are maintained in a fixed relationship while the space betweenthem is filled with an insulating substance.

A further object of the invention is to provide a railway tank car and amethod of making the same, wherein there is provided a plurality ofbarriers disposed between the inner liner and the outer shell whichdefine several fluid-tight compartments.

Further features of the invention pertain to the particular arrangementof the elements of the railway tank car and of the steps of the methodof making the same, whereby the aboveoutlined and additional operatingfeatures thereof are attained.

The invention, both as to its organization and method of operation,together with further objects and advantages thereof, will best beunderstood by reference to the following specifications, taken inconnection with the accompanying drawings, in which:

FIG. 1 is a side elevational view of a railway tank car embodying thepresent invention, certain portions thereof being broken away to exposethe inner liner;

FIG. 2 is a view of the inner liner of the tank car with a plurality ofannular barriers thereon and with the outer shell sections being slidinto place;

FIG. 3 is a side elevational view of the railway tank car with the outershell in place and with a suspension apparatus supporting the innerliner;

FIG. 4 is a greatly enlarged view of the car in FIG. 2, along the lines44 thereof;

FIG. 5 is a greatly-enlarged view of the portion of FIG. 3 in the circlelabeled with the reference numeral 5, and illustrating the manner inwhich the outer shell compresses the flexible barrier;

FIG. 6 is an enlarged vertical section of the body of the railway tankcar, this view being taken in the direction of the arrows along the line6-6 in FIG. 3;

FIG. 7 illustrates the suspension apparatus and the manner in which itis attached to the railway tank car; and

FIG. 8 is the vertical section of the suspension apparatus and the bodyof the railway tank car shown in FIG. 7, taken along the lines 8-8thereof.

Referring now to the drawings and more particularly to FIGS. 1 and 2thereof, the railway tank car 10 there illustrated, and embodying thefeatures of the present invention, is of the heat-insulating type and ofa construction that does not include an underframe. More particularly,the railway tank car 10 comprises an elongated longitudinally extendingbody 11 disposed in a substantially horizontal position. The oppositelower end portions of the body 11 respectively carry two arcuate-shapedsaddle plates 12 that are rigidly secured thereto, asby welding. Each ofthe saddle plates 12 comprises a base section 13 disposed directly belowthe adjacent end of the body 11, and a pair of arm sections 14respectively disposed below the opposite side portions of the adjacentend of the body 11. In-turn, two longitudinally extending and alignedstub draft sills 15 are respectively disposed below the base sections 13of saddle plates 12 and rigidly secured thereto, as by welding. In turn,the two stub draft sills 15 are respectively carried by two laterallyextending body bolsters l6 rigidly secured thereto, as by welding. Eachof the body bolsters 16 carries a pair of upstanding pedestals 17rigidly secured thereto adjacent to the opposite ends thereof, as bywelding; and each of the pedestals I7 is rigidly secured to the adjacentarm section 14 of the associated saddle plate 12. Thus, each of the stubdraft sills 15 is rigidly secured to the adjacent end portion of thebody 11 by the adjacent saddle plate 12, the adjacent body bolster l6,and the'adjacent pair of pedestals 17. The stub draft sills 15 arearranged in longitudinal alignment with each other and with the centerline thereof disposed in a vertical plane passing through thelongitudinal center of the body 11. The body bolsters 16 arerespectively supported by truck bolsters respectively carried by wheeledtrucks 18 respectively disposed therebelow, each of the body bolsters 16being connected to the adjacent truck bolster by a center pin, notshown, so as to accommodate articulation of the truck 18 with respect tothe associated body bolster 16 in a conventional manner. Also, the outerends of the respective stub draft sills 15 are hollow and are adaptedrespectively to receive conventional draft gears, not shown, in aconventional manner. In view of the foregoing description of thearrangement of the stub draft sills 15 and the associated elements, itwill be appreciated that the railway tank car 10 does not comprise theusual underframe; whereby the draft and buff forces are applied betweenthe stub draft sills 15 through the body 11, without the provisions ofan underframe or any other equivalent rigid auxiliary structureinterconnecting the stub draft sills l5.

' The body 11 of the railway tank car 10 consists of an outer shell 20of strong rigid self-supporting structure, an inner liner 30 offluid-tight construction, and an intermediate layer of insulatingsubstance 50 filling the space between the inner liner 30 and the outershell 20, the general configurations of the elements 20, 30 and 50 beingsimilar. The outer shell 20 consists of two outer shell sections 21 thatare substantial duplicates of each other, whereby the followingdescription with respect to the left-hand shell section 21, as viewed inFIG. 1, is equally applicable to the right-hand outer shell section.Each outer shell section 21 includes three cylindrical side walls 22that are welded together to form seams 23. Disposed on the outer end ofthe last of the side walls 22 is an end wall 24 which has a generallyoutwardly convex or bell-like configuration, and is welded to the outerend of the left-hand side wall 22 to form a seam 25.

The inner liner 30 has a welded construction and is formed of low carbonsteel provided with an interior plastic coating or of suitable stainlesssteel for various corrosive ladings, etc. Also, the interior surface ofthe liner 30, when formed of stainless steel, is free of all cracks andsurface irregularities, and is provided with a smooth-mirror-likefinish, so as to provide a surface in contact with the contained ladingthat may be easily maintained in a clear, clean and sanitary condition,in order to prevent any possible contamination of the contained lading.In the instant construction, the inner liner 30 has a tubular side wall31 disposed in a substantially horizontal position and a pair ofupstanding end walls 32 respectively disposed on the opposite ends ofthe side wall 31. The side wall 31 is substantially cylindrical; and theend walls 32 are identical, each having a generally outwardly convex orbell-like configuration. There is provided a plurality of longitudinallyspaced-apart annular barriers 40 secured to the inner liner 30, theconstruction of which will be explained in more detail hereinafter. Forthe present, suffice to say that the barriers 40 are of a constructionto provide a number of fluid-tight compartments between the inner liner30 and the outer shell 20 and between adjacent ones of the barriers 40.The insulating substance 50 then fills each of these compartments.

Finally, there is provided a pair of longitudinally spacedapart manwaystructures 60 on the top of the body 11 respectively on either side of alateral plane passing through the center thereof. Each manway structure60 comprises an upstanding tubular manway 61 carrying a flat annular rim62 (see FIG. 3). Also, a cover 63 is associated with the top end of eachmanway structure 60 and is hingedly mounted thereon to enable it to bemoved between its open and closed position with respect to the upper endof the tubular manway 61. A substantially saddle-shaped ring 64 iscarried by the top central portion of the outer shell 20 in surroundingrelationship with a hole therein, through which the upstanding tubularmanway 61 projects, which ring 64 is rigidly secured in place, as bywelding.

Considering now the method of making the railway tank car body 11 inaccordance with the present invention, and referring to FIGS. 2, 3, and8, the inner liner 30 is first assembled by securing together, bywelding or the like, the various portions thereof. The two manwaystructures 60 are secured in place on top of the inner liner 30, throughwhich access may be gained to the interior. In the form of the inventionshown, the inner liner 30 is constructed in such a manner that thebottom portion of the side wall 31 slopes toward the center. An outletopening may be provided in the bottom of the side wall 31 approximatelycentrally thereof, whereby fluid in the liner 30 will flow naturallytoward such opening.

A plurality of barriers 40 is then wrapped or placed around the innerliner 30 in longitudinally spaced-apart relationship. Referringspecifically to FIGS. 4 and 5, each barrier 40 includes an annular rigidportion 41 that has a rectangular lateral cross section and is securedto the inner liner 30 by means of an adhesive 42. Each barrier 40 alsoincludes a flexible portion 43 that is U-shaped in lateral crosssection, the portion 43 including an annular body 44 and annular walls45. The flexible portion 43 is secured to the outer surface of the rigidportion 41 by means of an adhesive 46. Finally, there is provided astrap 47 that fits within the annular wall 45 and against the body 44 tohold securely the flexible portion 43 and the rigid portion 41 at theselected position on the liner 30.

Preferably, the adhesive 42 is applied to the exterior of the innerliner 30 and the inner surface of the rigid portion 41. After theadhesive 42 is allowed to set, the rigid portion 41 is wrapped on theinner liner 30. An adhesive is then applied to the outside surface ofthe rigid barrier 41 and also to the inside surface of the flexibleportion 43. After the adhesive is permitted to set, the flexible portionis wrapped around the rigid portion 41. Finally, the strap 47 is placedbetween the annular walls 45 of the flexible portion 43 and is drawntaut. The arrangement just described causes the barrier 40 to be securedtightly to the inner liner 30. Each of the barriers 40 is secured, oneafter another, in a similar manner, or if desired, the adhesive 42 canbe deposited on each location on the inner liner 30, followed byapplying the adhesive 42 to the rigid portion 41; then positioning allof the rigid portions 41 on the inner liner 30; followed by applyingadhesive to the outer surfaces of all of the rigid portions 41, and tothe inner surfaces of the flexible portions 43; followed by positioningthe flexible portions 43 in place on the outer surface of the rigidportions 41; and finally, by affixing the straps 47 respectively to thebarriers 40.

Preparatory to assembling the outer shell 20, the exterior of the innerliner 30 may be blasted by sand or the like to provide a good bond tothe insulating substance 50 which will later be applied.

In order to support the inner liner 30 while the outer shell 20 is beingslid into place, a suspension apparatus is provided. The suspensionapparatus 70 includes a pair of channelshaped members 71 respectivelyhaving their flanges outwardly directed and their bight portions inspacedrelationship. An elongated plate 72 is disposed between thechannelshaped members 71 and secured thereto, as by welding. Atriangular portion-of the plate 72 protrudes above the channelshapedmembers 71 and'has centrally therein an oval-shaped opening 73. A pairof U-shaped reinforcing members are disposed upside down respectively onopposite sides of the plate 72 and secured thereto, as by welding. Thesuspension apparatus 70 further includes four spacer assemblies 75secured to the channel-shaped members 71 at longitudinally spaced-apartpoints thereon, which points are selected to correspond to the positionsof the two manway structures 60. Each spacer assembly 75 includes a pairof laterally spacedapart'posts 76 secured at their tops and at theirbottoms respectively to a pair of crossbars 77. The top crossbar 77 ofeach of the four spacer assemblies 75 is secured to the outwardlydirected flanges on the channel-shaped member 71, as by welding. Thebottom crossbars 77 on the two spacer assemblies 75, toward the right,as viewed in FIGS. 3 and 7, are secured by means of fasteners 78, suchas nuts and bolts, to the manway structure 60 toward the right, asviewed in FIG. 7; and the bottom crossbars 77 of the spacer assemblies75, toward the left as viewed in FIG. 7, are secured by similarfasteners 78 to the manway structure 60 toward the left. Finally, thereis provided a cable 79 carrying a hook 80, which cable is secured to anoverhead structure (not shown). The hook 80 is slipped through thereinforcing members 74 and the opening 73 in the plate 72, thereby tosuspend the inner liner 30 for subsequent steps in its processing.

The next step involves the positioning of the outer shell 20 on theinner liner 30. As previously stated, the outer shell 20 consists of twoouter shell sections 21 which are substantial duplicates of each other.Referring to FIG. 2, the outer shell section 21 that is to encase theleft-hand portion of the'inner liner 30 is placed, such that its openend is in facing relationship with the left end wall 32 of the innerliner 30, as viewed in FIG. 2, and such that the longitudinal axis ofthe outer shell section 21 is essentially colinear with the longitudinalaxis of the inner liner 30. Referring specifically to FIG. 4, it isimportant to note that the outer diameter of each of the annular walls45 of each of the barriers 40 is greater than the inner diameter of theouter shell 20, when the barrier 40 is in an unflexed condition. Statedanother way, the distance between the longitudinal axis of the innerliner 30 and the outside surface of the flexible portion 43 is greaterthan the inside radius of the outer shell 20. Thus, as the outer shellsection 21 on the left is being slid into place, a wiping action betweenthe flexible portion 43 and the outer shell section 21 is created. Theouter shell section 21 thus comprises radially the annular walls 45 tocause the barrier 40 to assume the condition shown in FIG. 5. Of course,as the outer shell section 21 on the left is .moved further toward theright, it encounters the second barrier 40a, and causes compression ofthe flexible portion 43 in a similar manner. It can thus be appreciatedthat there is defined a compartment between the first barrier 40 andsecond barrier 40a and between the outer surface of the inner liner 30and the inner surface of the outer shell 20, this compartment beingfluid-tight by virtue of the radial compression of the annular walls 45.The outer shell section 21 is urged further to the right until itencounters the third barrier 40b, whereupon its flexible portion 43 isalso radially compressed to define yet a second fluid-tight compartmentbetween the second barrier 40a and the third barrier 40b and between theinner liner 30 and the outer shell section 21. When the outer shellsection 21 is finally in place, as shown in FIG. 3, three fluid-tightcompartments are defined, respectively between the inner liner 30 andthe outer shell 20 to the left of the first barrier 40, a secondcompartment between the first barrier 40, and the second barrier 40a,and a third compartment between the second barrier 40a and the thirdbarrier 40b.

After the left-hand outer shell section 21 is in place, the right-handouter shell section 21 is then slid into place in a similar fashion.More particularly, the outer shell section 21 that is to encase theright-hand portion of the inner liner 30 is placed such that its openend is in facing relationship with the right end wall 32 of the innerliner 30, as viewed in FIG. 2, and such that the longitudinal axis ofthe outer shell section 21 is essentially collinear with thelongitudinal axis of the inner liner 30. As was the case with thebarrier 40 to the left, the outer diameter of each of the annular walls45 of each of the barriers 40 toward the right is greater than the innerdiameter of the outer shell 20, when the barrier 40 is in an unflexedcondition. Stated another way, the distance between the longitudinalaxis of the inner liner 30 and the outside surface of the flexibleportion 43 is greater than the inside radius of the outer shell 20.Thus, as the outer shell section 21 on the right is being slid intoplace, a wiping action between the flexible portion 43 and the outershell section 21 is created. The outer shell section 21 thus compressesradially the annular walls 45 to cause the barrier 40 to assume thecondition shown in FIG. 5. As the outer shell section 21 on the left ismoved further toward the right, it encounters the second barrier 40a,and causes compression of the flexible portion 43 in a similar manner.It can thus be appreciated that there is defined a compartment betweenthe first barrier 40 and second barrier 40a and between the outersurface of the inner liner 30 and the inner surface of the outer shell20, this compartment being fluid-tight by virtue of the radialcompression of the annular walls 45. The outer shell section 21 is urgedfurther to the left until it encounters the third barrier 40b, whereuponits flexible portion 43 is also radially compressed to define yet asecond fluid-tight compartment between the second barrier 40a and thethird barrier 40b and between the inner liner 30 and the outer shellsection 21. When the outer shell section 21 is finally in place, asshown in FIG. 3, three fluid-tight compartments are defined,respectively between the inner liner 30 and the outer shell 20 to theleft of the first barrier 40, a second compartment between the firstbarrier 40, and the second barrier 40a. and a third compartment betweenthe second barrier 40a and the third barrier 4012.

Alternatively, the outer shell sections 21 may be simultaneously alignedwith the respective ends of the inner liner 30 and simultaneously movedtoward each other until they converge at the center line.

Each outer shell section 21 has a U-shaped opening 22a formed near theopen end thereof, the width of that opening being slightly greater thanthe diameter of the tubular manway 61. The length of the opening 22a isapproximately equal to the distance between the mid-point of the innerliner 30 and the outermost point on the tubular manway 61. The curvatureof the bight portion of the opening 22a matches the curvature of thetubular manway 61. Accordingly, when the outer shell sections 21 areslid onto the inner liner 30, the tubular manway 61 will be locatedrespectively in the openings 22a. When the outer shell sections 21 arein place, the outer ends of the tubular manways 61 will respectivelyabut against the curved bight portions of the openings 22a. To fill thegap in the outer shell 20 between the tubular manways 61, there isprovided a curved cover plate 29 having a curvature to conform to thecurvature of the outer shell 20, the ends being concavely curved tomatch the curvature of the tubular manway 61. The cover plate 29 isplaced, as shown in FIG. 3, and then secured, as by welding to the outershell 20.

After both outer shell sections 21 are in place, a bar 81 of properlength is secured temporarily to the channel-shaped members 71 at oneend thereof and to the portion of the outer shell section 21 immediatelytherebelow, the bar 81 being secured such as by welds. Similarly, asecond bar 81 is secured temporarily to the left-hand end of thechannel-shaped menibers 71 and to the portion of the outer shell 20immediately therebelow, such as by welds. The bar 81 effectively holdsthe outer shell section 21 in the desired relationship with respect tothe inner liner 30. After the bar 81 is secured in place, the two outershell sections 21 are welded together to form the seam 26. This latterstep could easily have been performed prior to the connection of thebars 81. Of course, once the two outer shell sections 21 are securedtogether, an additional fluid-tight compartment between the thirdbarrier of each outer shell section 21 is provided, for a total of sevencompartments in all.

The uncured ingredients used to form the insulating substance 50 arethen introduced through pour holes 27 which are located atlongitudinally spaced-apart points in the outer shell 20. Thus, there isat least one pour hole 27 communicating with each of the sevencompartments defined by the barriers 40, the inner liner 30 and theouter shell 20. Also, there is provided one or more air vents 28communicating with each compartment to facilitate the introduction ofthe uncured ingredients. The ingredients once in the compartments set uprather quickly at room temperature to produce the insulating substance50. Thereafter, the pour holes 27 and the air vents 28 are sealed byplugs, plates, or the like. The bars 81 that form part of the suspensionapparatus 70 are disconnected from the outer shell 20, and then thefasteners 78 are loosened to remove the suspension apparatus 70.Thereafter, the stub draft sills 15 are welded to the saddle plates 12,the body bolsters 16 are welded to the stub draft sills 15, and thepedestals 17 are welded both to the body bolsters 16 and to the saddleplates 12, thereby to finish the principal elements of the draftstructure for the railway tank car 10. Usually, the draft sills, thebolsters and the saddle plates are welded in place prior to the bringingtogether of the outer shell sections. Finally, the body 11 carrying thestub draft sills 15, etc. is mounted upon the associated wheel trucks18.

In the operation of the railway tank car 10, the inner liner 30 isadapted to receive cold ladings having temperatures as low as about 50F.; and it is undesirable to refrigerate the lading during several daysof transit of the car 10; and it is required that the temperature riseof the lading be limited to several degrees F. even when the ambienttemperature is as high as F. Also, in the operation of the railway tankcar 10, the inner liner 30 is adapted to receive hot ladings havingtemperatures as high as 300 F.; and it is undesirable to heat the Iadingduring several days of transit of the car 10; and it is required thatthe temperature fall of the lading be limited to several degrees F. evenwhen the ambient temperature is as low as 0 F. In order to meet thisdifficult specification, it is desirable that the resin forming theinsulating layer 50 comprises a polyester-urethane resin of closed-cellstructure entrapping substantial inert gas selected from the classconsisting of a chlorine-fluorine substituted alkane; whereby this resinhas a K-factor at least as low as about 0.15 B.t.u./in./sq.ft./hr./ F.in order to heat-insulate from each other the outer shell 20 and theinner liner 30.

Reverting to the inert gases specified, this class of compoundscomprises CHC1F CI-IC1 F, CC1 F CCI F, C C 1 F 4 and C C1 F and of thesegases CC1 F and CC1 F are normally preferred as a matter of efficiencyand economy. The utilization of these inert gases as the blowing agentis important since a typical polyester-urethane resin blown with CC 1 Fhas a K-factor as low as about 0.122, while a comparable typicalpolyester-urethane resin blown with CO has a K-factor of about 0.191.For reference purposes it is noted that a comparable cellularpolystyrene resin has a K-factor of about 0.220.

The following example of a polyester-urethane resin of cellular form andof closed-cell structure and blown by an inert gas of the classspecified is recommended for the production of the insulating layer 50.This resin is produced in a conventional manner'employing a well-knownmachine comprising tanks A and B respectively containing two portions ofthe ingredients, as noted below. The contents of tank A are maintainedat a temperature of about 70 F. and the contents of PartsTrichloromonofluoromethane,

Freon-Al l" (DuPont) 27 Tolylene diisocyanate,

"70 Nacconate 4040 (Allied Chemical) 71-% Silicone compound, "L530"(Union Carbide) 1-% Tank B contains the ingredients in parts by weight:

100 parts chlorinated polyester, Hetrafoam 250 (Durez Plastics) ln tankA the trichloromonofluoromethane is a propellant and blowing agent, andthe silicone compound is an agent for controlling the cell structure ofthe cured polyester-urethane resin; and in tank B the chlorination ofthe polyester renders the cured polyester-urethane resin flameself-quenching. This polyester in tank B essentially comprises the basicreaction product of maleic anhydride and phthalic anhydride withpropylene glycol; a typical formula comprising 0.5 mole maleicanhydride, 0.5 mole phthalic anhydride, and 1.1 moles of propyleneglycol. A small amount of cobalt napthenate, as an accelerator, and asmall amount of methyl ethyl ketone peroxide, as a catalyst, may also beadded to the basic ingredients named above for the fundamental purposeof controlling the degree of prepolymerization thereof in the productionof this linear polyester. Also, the chlorination of this linearpolyester is normally carried out subsequent to the prepolymerizationmentioned and may be omitted if the flame self-quenching characteristicnoted is not desired in the ultimately produced polyester-urethaneresin. However, this characteristic is highly desirable, as it increasesthe safety factor of the resin and contributes to chemical stabilitythereof when it is subjected to relatively high temperatures. This blownpolyester-urethane resin after curing has a density of about 2lbs./cu.ft.

The foregoing examples of the polyester-urethane resin are well knownwithin themselves and form no part of the present invention; wherebythese formulations have been set forth herein only by way of examples,so as positively to insure that the corresponding resins incorporated inthe railway tank car possess the desiredchemical and physical propertiesthat are required therein, as previously explained in conjunction withthe construction and arrangement thereof. Thus, it will be readilyapparent that other conventional and well-known chemical formulations ofthese polyesterurethane resins may be substituted in the railway tankcar 10.

In a constructional example of the railway tank car 10: the outer shell20 had an overall lengthof 627 inches; each outer shell section 21 hadan overall length of 313% inches and had an inside diameter of 115inches at its open end and 112 inches at its closed end so that eachouter shell section 21 sloped downwardly toward the mid-point of thebody 11; the

. inner liner 30 had an overall length of 614% inches, an insidediameter of 102 inches at its mid-point and 99 inches at its outerextremities, whereby the bottom of the inner liner 30 slopes toward themid-point thereof a total of 3 inches from either end; the inner liner30 is spaced substantially uniformly inwardly of the outer shell 20, sothat the insulating substance 50 has a substantially-uniform thicknessof approximately 6 5/16 inches; the rigid portion 41 of each barrier 40is constructed of urethane foam and when viewed in lateral cross sectionmeasures 4 inches X 8 inches; each flexible portion 43 of the barriers40 is constructed of expanded polyethylene foam wherein the radial widthof the annular walls 45 when viewed in lateral cross section is 2%inches when uncompressed and 2 5/16 inches when compressed; the distancebetween the outside surface of the inner liner 30 and the inside surfaceof the outer shell 20 is 6 5/16 inches; the distance between one end ofthe inner liner 30 and the center line of the adjacent barrier 40 is 69inches; the distance between the center lines of barrier 40 and thebarrier 40a is 93 inches; the distance between the center lines of thebarrier 40b and the barrier 40c is 92 inches; the distance between thecenter lines of the two barriers 40:: is 106 /2 inches the total amountof insulation required to make up the insulating substance 50 is' 797cubic feet; the outer shell 20 is formed with low-carbon steel, having athickness of 7/ 16 inch and is of welded construction; and the innerliner 30 is formed of low-carbon steel, having a thickness of 3/16 inchand is of welded construction. Also, the interior surface of the innerliner 30 carries a substantially uniform baked phenolic coating, havinga thickness in the general range 0.010 to 0.030 inch.

In view of the foregoing, it is apparent that there has been provided animproved method of making a railway tank car of the heat-insulated typeand may be carried out in a simple and economical manner.

While there has been described what is at present considered to be thepreferred embodiments of the invention, it will be understood thatvarious modifications may be made therein, and it is intended to coverin the appended claims all such modifications that fall within the truespirit and scope of the invention.

What is claimed is: p

1. A railway tank car comprising an elongated inner liner, an elongatedouter shell encircling said inner liner and spaced therefrom, aplurality of substantially rigid annular barriers secured to the outersurface of said inner liner at longitudinally spaced-apart pointsthereon and each extending around the girth of said liner, acorresponding plurality of substantially flexible annular barriersdisposed between said outer shell and said rigid barrier and securedrespectively to the outer surface of said rigid barriers and extendingtherearound, the combined radial thickness of said rigid barrier andsaid flexible barrier in the unflexed condition thereof being greaterthan the radial distance between said inner liner and said outer shell,thereby to define separate fluid-tight compartments between said innerliner and said outer shell and separated one from the other by saidbarrier, and an insulating substance in said compartments.

2. The railway tank car set forth in claim 1, wherein said rigid barrieris a urethane foam.

3. The railway tank car set forth in claim 1, wherein said flexiblebarrier is an expanded polyethylene foam.

4. A railway tank car comprising an elongated inner liner, an elongatedouter shell encircling said inner liner and spaced therefrom, aplurality of substantially rigid annular barriers secured to the outersurface of said inner liner at longitudinally spaced-apart pointsthereon and each extending around the girth of said liner, acorresponding plurality of substantially flexible annular barriersdisposed between said outer shell and said rigid barriers and securedrespectively to the outer surfaces of said rigid barriers and extendingtherearound, each of said flexible barriers being U-shaped in transversecross section and including a body carrying a pair of spaced radiallyextending walls, the combined radial thickness of said rigid barrier andsaid flexible barrier in the unflexed condition thereof being greaterthan the radial distance between said inner liner and said outer shell,said walls being compressed by said outer shell thereby to defineseparate fluid-light compartments between said inner liner and saidouter shell and separated one from the other by said barrier, and aninsulating substance in said compartments.

5. A railway tank car comprising an elongated inner liner, an elongatedouter shell encircling said inner liner and spaced therefrom, aplurality of substantially rigid annular barriers secured to the outersurface of said inner liner at longitudinally spacedeapart pointsthereon and each extending around the girth of said liner, acorresponding plurality of substantially flexible annular barriersdisposed between said outer shell and said rigid barriers and securedrespectively to the outer surfaces of said rigid barriers and extendingtherearound, each of said flexible barriers bein'g U-shaped intransverse cross section and including a body carrying a pair of spacedradially extending walls, and a band positioned between said walls andagainst said body and tightened secure-

1. A railway tank car comprising an elongated inner liner, an elongated outer shell encircling said inner liner and spaced therefrom, a plurality of substantially rigid annular barriers secured to the outer surface of said inner liner at longitudinally spaced-apart points thereon and each extending around the girth of said liner, a corresponding plurality of substantially flexible annular barriers disposed between said outer shell and said rigid barrier and secured respectively to the outer surface of said rigid barriers and extending therearound, the combined radial thickness of said rigid barrier and said flexible barrier in the unflexed condition thereof being greater than the radial distance between said inner liner and said outer shell, thereby to define separate fluid-tight compartments between said inner liner and said outer shell and separated one from the other by said barrier, and an insulating substance in said compartments.
 2. The railway tank car set forth in claim 1, wherein said rigid barrier is a urethane foam.
 3. The railway tank car set forth in claim 1, wherein said flexible barrier is an expanded polyethylene foam.
 4. A railway tank car comprising an elongated inner liner, an elongated outer shell encircling said inner liner and spaced therefrom, a plurality of substantially rigid annular barriers secured to the outer surface of said inner liner at longitudinally spaced-apart points thereon and each extending around the girth of said liner, a corresponding plurality of substantially flexible annular barriers disposed between said outer shell and said rigid barriers and secured respectively to the outer surfaces of said rigid barriers and extending therearound, each of said flexible barriers being U-shaped in transverse cross section and including a body carrying a pair of spaced radially extending walls, the combined radial thickness of said rigid barrier and said flexible barrier in the unflexed condition thereof being greater than the radial distance between said inner liner and said outer shell, said walls being compressed by said outer shell thereby to define separate fluid-light compartments between said inner liner and said outer shell and separated one from the other by said barrier, and an insulating substance in said compartments.
 5. A railway tank car comprising an elongated inner liner, an elongated outer shell encircling said inner liner and spaced therefrom, a plurality of substantially rigid annular barriers secured to the outer surface of said inner liner at longitudinally spaced-apart points thereon and each extending around the girth of said liner, a corresponding plurAlity of substantially flexible annular barriers disposed between said outer shell and said rigid barriers and secured respectively to the outer surfaces of said rigid barriers and extending therearound, each of said flexible barriers being U-shaped in transverse cross section and including a body carrying a pair of spaced radially extending walls, and a band positioned between said walls and against said body and tightened securely to mount said flexible barrier upon said rigid barrier, the combined radial thickness of said rigid barrier and said flexible barrier in the unflexed condition thereof being greater than the radial distance between said inner liner and said outer shell, said walls being compressed by said outer shell thereby to define separate fluid-tight compartments between said inner liner and said outer shell and separated one from the other by said barrier, and an insulating substance in said compartments. 